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Sir, I am given to understand that Dhruv is optimised for high altitudes which doesn't allow the engines to be used in full potential at sea level. is there any current plan to address this issue, which might mean better utilization of naval Dhruv ?thanks.

Rahul M wrote:Sir, I am given to understand that Dhruv is optimised for high altitudes which doesn't allow the engines to be used in full potential at sea level. is there any current plan to address this issue, which might mean better utilization of naval Dhruv ?thanks.

I suppose main change will be a redesigned MGB. I never understood why we dont have a Naval varient of Dhruv for all these years.

Rahul M wrote:Sir, I am given to understand that Dhruv is optimised for high altitudes which doesn't allow the engines to be used in full potential at sea level. is there any current plan to address this issue, which might mean better utilization of naval Dhruv ?thanks.

At first glance, the practise of de-rating engines for good high altitude performance appears to be contradictory to the Navy's sea-level requirement. However, it really is not so. The reason is as under:- The Navy's prime requirement for a weaponised helicopter is Anti-sub duties, which essentially requries dunking sonar operations. This requires the helicopter to hover for prolonged periods with the sonar in the water and re-position periodically to a new hover postion and so on. A large part of the flight is thus spent at hover, in hot and humid weather.The conditions for hover with sonar dunked is such that the helicopter is at a considerable height and is at Out-of-Ground (OGE) conditions. This requires considerable power from the engines, which in turn must provide the required power at Continuous Power or Cruise Power, to ensure the engines can sustain the hover for long periods of time and do not require frequent removals for maintenance / overhaul, which would have happened if say, the engines were spooled up to take-off power, every time the helicopter hovered for sonar dunking. Therefore, a helicopter with good installed power (including de-rated engines) will naturally be optimised for the role. In fact, the navy's Ka-28 has suprisingly good high altitude hover performance, partly due to good installed power.

The Dhurv's de-rated powerplants is therefore not a disadvantage for the role. Its main rotor blade folding for ship-borne use is being further optimised for minimising its footprint on deck. That is a work-in-progress primarily due its hingeless flex-beam rotor does not lend itself easily to such modifications.

I believe manual folding has been there since inception that isnt much of an operational challenge in an Aircraft Carrier with large hanger & deck. The challenge is automatic folding that is a must on smaller frigates and corvettes where the rotor diameter may exceed beam of the ship making manual folding risky, especially in high sea states.

Beam of Talwar 15.2 meters Brahmaputra 14.5 meters Kamorta 13.7 meters Saryu 12.9 meters. This beam will further reduce at the stern. Dhruv with rotor diameter 13.2 meters will make manual folding operations hazardous with less clearance in Kamorta and Saryu classes, especially in high sea states, despite the blades being at 45 degree angle to the beam.

The manual main rotor blade folding of the Black Hawk was changed to an automatic system to avoid having crewmen working at the rotor head during high sea state, hazardous conditions. A significantly lighter electrically powered blade fold system was chosen over the typical hydraulic approach.

A system for winching the aircraft down and securing it to the ship’s deck during high sea state conditions was developed for the SH-60B. Called the Recovery, Assist, Secure and Traversing (RAST) system, it enabled the Seahawk to be recovered in sea states up to 5 (33 knot winds, 13 ft. swells, 6 degrees of pitch, 15 degrees of roll conditions). This system was a refinement of the Beartrap haul-down system developed by the Royal Canadian Navy during the mid-1960s.

During RAST operations, the helicopter lowers a messenger cable that is connected to the ship’s haul-down cable, which is then raised and locked into the helicopter’s RAST probe. A 4000 lb. force is applied to the haul-down cable, which guides the probe into the locking beams of the Rapid Securing Device that also moves the helicopter into and out of the hanger.

I did not completely follow the reasoning. With a MGB which can take the max power of the engine at sea level, wouldn't you have even more power at your disposal while hovering with a submerged dunking sonar?

I did not completely follow the reasoning. With a MGB which can take the max power of the engine at sea level, wouldn't you have even more power at your disposal while hovering with a submerged dunking sonar?

Saar,The fundamental Q one needs to ask for the dunking sonar role is: Can the helicopter’s engines provide the power required at a maximum of cruise or max continuous power (which is a non-time rated power level), with the helicopter kitted out in the required sonar configuration and with fuel required for the specified time on station?

If this answer is yes, then the design of the helicopter is in the reckoning.

Then comes other equally important aspects, such as control and handling (including crosswinds), avionics including autopilot for automated transition to hover, auto-hover, etc for night op, ship borne footprint and other related requirements, blah, blah….The ALH Mk-III already fits the above bill.

If the designer now changes the MGB to accept more power from the de-rated engines, then there is an attendant weight increase, increase / change in tail rotor transmission and tail rotor, more fuel required for higher power from engines and so on. Also we need to keep in mind that beyond an optimal point, even if we pump in more power to the main rotor, its thrust peaks off and then we need to increase the rotor diameter or add another blade…

Kartik wrote:Hari Nair sir, I had read somewhere that there was a plan to install a Longbow like fire control radar on the LCH. Is that a capability that is actually planned for the LCH?

Its controlled tech. So far, only the Yanks have successfully deployed it. Its also a very expensive piece of kit and makes up a very large chunk of the bill for the AH-64E, so I am given to understand. I am not sure whether they are amenable to export only the FCR for fitment on other platforms.

I am not aware of an in-country programme for an MM FCR.

The Russians have something close to deployment, it appears from the news.Also, our Chinese friends have something in development for their home-grown Attack Helicopter Zhi-10.

I agree with you that:1. ALH has sufficient power at SL. 2. Changing the MGB is no easy task. Even if the MGB is redesigned, the rotors have to be redesigned too, meaning the tail rotor has to change too.3. Changing the above three is the same as changing the whole helicopter.4. Such a helicopter will maximize performance at SL, but high altitude performance will suffer.

Brings me to the core of my question:How long should we strive to have one design for these orthogonal requirements of high and low altitude flying? I understand that this might be a rhetorical question. Just want to know your opinion.

Hari sir,For IMRH ,two versions one for IAF/IA with 12.5 T MTOW and payload of 4T and altitude ceiling of 6km while for IN with 11.25 T MTOW and payload of 3.5 T and altitude ceiling of 4.5 km is planned.One can infer that the IN version had proportionally smaller footprint of the rotor apart from being lighter while the range and cruise speed remains same. What about MGB and engine. Kindly explain.

I agree with you that:1. ALH has sufficient power at SL. 2. Changing the MGB is no easy task. Even if the MGB is redesigned, the rotors have to be redesigned too, meaning the tail rotor has to change too.3. Changing the above three is the same as changing the whole helicopter.4. Such a helicopter will maximize performance at SL, but high altitude performance will suffer.

Brings me to the core of my question:How long should we strive to have one design for these orthogonal requirements of high and low altitude flying? I understand that this might be a rhetorical question. Just want to know your opinion.

-If I may repeat my earlier statement:The fundamental Q one needs to ask for the dunking sonar role is: Can the helicopter’s engines provide the power required at a maximum of cruise or max continuous power (which is a non-time rated power level), with the helicopter kitted out in the required sonar configuration and with fuel required for the specified time on station?

Emphasis added to highlight that the design will be tailored to cater to the user specified requirements and user defined missions. That's the design's raison d'être!

If the answer to the question above is yes, then the design of the helicopter is in the reckoning. If that same helicopter can also take benefit of high installed power and light-weight transmission at high altitude, then its all the better.

If it cannot, then the design needs change.

That is the bottom-line!

Designs are made to be role / mission specific for military and market requirements specific for the civil. Take the hypothetical example you made of maximising sea level performance. Say we design it for the civil and if you keep increasing the size / payload just with an intent to max the performance at sea level, then will the market support the increased seat / cargo capacity with attendant increased costs in both capital and operational ? Again, what exactly do we mean by 'max' performance at sea level.? Performance at hover (lifting max payload) requires a different set of design parameters as compared to maximising cruise speed. So which is more important? What should the design cater to? The answer : the specific market segment which is targetted will have its own peculiar flight profile and our design will need to cater to that specific requirement. If say, quick transit time is a priority to reach far-flung oil rigs, then a high cruise speed is a primary design requirement.

sankum wrote:Hari sir,For IMRH ,two versions one for IAF/IA with 12.5 T MTOW and payload of 4T and altitude ceiling of 6km while for IN with 11.25 T MTOW and payload of 3.5 T and altitude ceiling of 4.5 km is planned.One can infer that the IN version had proportionally smaller footprint of the rotor apart from being lighter while the range and cruise speed remains same. What about MGB and engine. Kindly explain.

Is HAL planning an improved variant beyond MkIII (I am aware of some of the continuous improvements). Incidentally, the changes we were discussing are exactly on the lines of what Eurocopter is doing from H145. No changes in the transmission, but they are are going for shorter 5-bladed rotor rather than 4-bladed design earlier. They could increase the MTOW by 100 kgs (payload by 150 kgs).

Any thoughts on a Fenestron or even a pusher-prop design. IA/IAF did show an inclination towards the latter in AI-19 seminar. Frankly, I am not a big fan of the KA-228 when we have our very own LUH. But, it would be very interesting if HAL would collaborate on Kamovs (projected) pusher prop designs.

How exactly does a wire strike protection system work? From filmi shoots, I thought main rotor or tail rotor were the ones to get entangled first. However, WSPS seems to protect against wire strikes near windshield. How effective is this? Looks like additional instruments are needed.

As discussed in section 3.1, there was a significant decrease in the number of wire strike accidents in U.S. military helicopters after the installation of WSPS. In addition, there were no fatalities in wire strike accidents after installing WSPS. While the reduction in the number of fatalities is due to the WSPS, it is conjectured that the reduction in the number of wire strike accidents is because the WSPS constantly alerts the pilot to possible wire strikes. WSPS is most effective when the helicopter impacts the wires nearly perpendicular to the wires in a level altitude and at flight speeds of more than 30 knots. WSPS is not available for all currently flying helicopters. As discussed in sections 3.2 and 3.3, WSPS can only be installed in about 25% of the helicopters. The other helicopters (e.g., Robinson R22, Robinson R44, Bell 47, and MD 369) cannot be equipped with WSPS. 42 During the years 1994-2004, there were 65 fatalities in wire strike accidents, in which 21 fatalities (32%) involved the Bell-206 helicopter. The AS 350 and the Bell 407 helicopters each had 4 fatalities (6%). Thus, assuming that the trend of the past 10 years continues in the coming years, and assuming that all the wire strike accidents occur in conditions when it is most effective, equipping helicopters with WSPS can reduce about 44% of the fatalities. However, this is an overestimate because most of the accidents occurred during the climb and descent phases of flight and involved wire strikes of the main rotor system, the tail boom, or the vertical tail.

Make in India: HAL offers Indian solution to Indian Navy’s requirement for Advanced Light Helicopter ‘Dhruv’-Huma Siddiqui

The Rs 21,738 crore deal for 111 Naval Utility Helicopter (NUH) proposed to be `Made in India’ could tip in favour of state-owned Hindustan Aeronautics Limited’s (HAL). A top officer told Financial Express Online “The Company’s NUH is an Advanced Light Helicopter `Dhruv’ with customisation designed to meet all the operational requirements of India.”

Earlier this year at the Aero India 2019, HAL had demonstrated the Tail Boom folding and Main Rotor folding of the Naval Utility Helicopter.

US-based Lockheed Martin’s Sikorsky Helicopters which has responded to the Express of Interest (EoI), is likely to drop out at the next level as it has multiple non-compliances. “Unless the Indian Navy dilutes its requirements at the Request for Proposal (RfP) Stage, the company might drop out since it is non-compliant to many of the specifications of the helicopter the navy is seeking,” a top official said.

Three companies Lockheed Martin’s Sikorsky Helicopter S 76D, European Airbus and Russia’s Kamov Ka 226T, have responded to the EoI floated by the defence ministry earlier this year. The companies last month submitted proposals to build their helicopters through an Indian industry designated as “strategic partner” (SP).

The European manufacturer Airbus has submitted proposals for two platforms – the H 145M and the Panther AS565 – to be manufactured in partnership with Mahindra Defence.

Under an Indo-Russian inter-governmental agreement (IGA), both HAL and Indo-Russian Helicopters Ltd (IRHL) already have a joint venture to manufacture the Kamov 226T light helicopter in India.

HAL on its own has offered its indigenous ALH for the NUH deal.

This will be the first acquisition under the SP procurement model when it is finalised. Under the SP model the OEM is expected to tie up with local Indian companies who are manufacturing major platforms in India with niche technologies and production knowhow supplied by a foreign OEM.

According to officials, Ministry of Defence (MoD) in the EoI has stated that the OEMs have been mandated to set up a dedicated manufacturing line, including design, integration and manufacturing processes for NUH in India. It had also said the OEM will have to make Indian manufacturing line as a global exclusive facility for the NUH platform being offered.

As has been reported by The Financial Express earlier in 2015, the Indian Navy had received as many as 10 bids from Indian companies for the NUH programme. However, in an effort to keep the process transparent, the navy had encouraged OEMs tying up with a single Indian partner.

Once the contract is finalised, 16 helicopters will come from the OEM directly and the balance will have to manufacture in India with almost 60 per cent indigenisation. In a process which will take a couple of months, all the technical bids will be scrutinised by the Indian Navy, before intensive trials start for evaluating the performance of each machine in different terrains and weather conditions.

The modified ALH should be ideal as NUH. It will be larger and more capable then all the other helicopters proposed. It will be able to carry much high loads or much more capable loads. For the NUH role, I guess the hover requirements would be less stringent, as it will be meant mainly for Search and Rescue type roles and not as the primary anti-sub helicopter. However, the ALH, might be able to take a secondary anti-sub role, much better then any of the other helicopters. Though for the utility role, the heli will have to have enough room for passengers and cannot cram the entire fuselage with equipment for anti-sub role. The ALH will be certainly better at carrying light weight torpedoes and other weapons then the Ka-226T or any other candidate.

How exactly does a wire strike protection system work? From filmi shoots, I thought main rotor or tail rotor were the ones to get entangled first. However, WSPS seems to protect against wire strikes near windshield. How effective is this? Looks like additional instruments are needed.

A large part of Dhruv is built by the Indian private sector!!! Why not bring up the private sector where we don't have Indian designed products. For example, NCAD is going nowhere. Mahindra and Tata are a step away from being able to field 18-seater commuters. How about a 70-seater RTA.

HAL has been trying to sell its two civil Do-228s. I see that corrigendum after corrigendum pushing the last date for bids out. HAL simply can't go down the Embraer route. Let's try that space with private companies.

India seems to be struggling with MALE/HALE UAVs. Let's get help there.

Make in India should not come at the cost of Made in India. I think the SP is pretty clear about this.

Why can't HAL be the OEM in this scenario. Keep everything of the SP model and just replace a foreign OEM with HAL. Provided ofcourse blades of ALH folds to IN's satisfaction.HAL can do so much more. Why does it needs to keep the Engine dept? Outsource the manufacturing to pvt and keep only RnD. We need a credible manufacturer of engines if we want to have our own TF someday. Tata already builds fuselages for Boeing. It can build full fuselages for HAL too.It can outsource assembly of components of helis too just like it doing with LCA. If HAL gets the job, I would like to see it handholding a pvt company for heli assembly.